Non-unitary representations of the SU(2) algebra in the Dirac equation with a Coulomb potential

A novel realization of the classical SU(2) algebra is introduced for the Dirac relativistic hydrogen atom defining a set of operators that, besides, allow the factorization of the problem. An extra phase is needed as a new variable in order to define the algebra. We take advantage of the operators to solve the Dirac equation using algebraic methods. To acomplish this, a similar path to the one used in the angular momentum case is employed; hence, the radial eigenfuntions calculated comprise non unitary representations of the algebra. One of the interesting properties of such non unitary representations is that they are not labeled by integer nor by half-integer numbers as happens in the usual angular momentum representation.Comment: 20 pages 1 eps figure in a single zipped file, submitted to J. Math. Phy

Feed form and energy concentration of the diet affect growth performance and digestive tract traits of brown-egg laying pullets from hatching to 17 weeks of age

The influence of feed form and energy concentration of the diet on growth performance and the development of the gastrointestinal tract (GIT) was studied in brown-egg laying pullets. Diets formed a 2 x 5 factorial with 2 feed forms (mash vs. crumbles) and 5 levels of energy differing in 50 kcal AMEn/kg. For the entire study (0 to 17 wk of age) feeding crumbles increased ADFI (52.9 vs. 49.7 g; P  0.05) by energy content of the diet. At 5, 10, and 17 wk of age, the relative weight (RW, % BW) of the GIT and the gizzard, and gizzard digesta content were lower (P < 0.05 to P < 0.001) and gizzard pH was higher (P < 0.05 to P < 0.001) in pullets fed crumbles than in pullets fed mash. Energy concentration of the diet did not affect any of the GIT variables studied. In summary, feeding crumbles improved pullet performance and reduced the RW of the GIT and gizzard, and increased gizzard pH at all ages. An increase in the energy content of the diet improved FCR from 0 to 17 wk of age. The use of crumbles and the increase in the AMEn content of the diet might be used adventageously when the objetive is to increase the BW of the pullets. However, crumbles affected the development and weight of the organs of the GIT, which might have negative effects on feed intake and egg production at the beginning of the egg laying cycle

Influence of the main cereal and feed form of the rearing phase diets on performance, digestive tract, and body traits of brown-egg laying pullets from hatch to 17 weeks of age

We hypothesize that pullets could respond similarly, independent of feed form, to the feeding of diets based on corn or wheat supplemented with adequate NSP enzymes. Also, pullets would quickly adapt their gastrointestinal tract and modify productive performance accordingly, when switched from crumbles to mash feeds. The aim of this research was to evaluate the effects of feeding crumbles for different periods of time, followed by feeding mash to 17 wk of age, on performance, gastrointestinal tract development, and body measurements of brown-egg laying pullets fed diets based on corn or wheat

Influence of noise level and seniority in the workplace on the SAL, ELI and percentage of hearing loss indices in the diagnosis and prevention of hearing loss in the working population

Introduction: This research relates the most important work-related factors affecting the development of hearing loss to the main methods used as medical assessment criteria in the diagnosis of occupational deafness. These criteria are the Speech Average Loss Index (SAL), the Early Loss Index (ELI) and the Percentage of Hearing Loss, and are applied to data obtained from audiograms performed on workers in occupational medical examinations. Method: Depending on the assessment method selected, these often return different results in grading an individual's hearing status and predicting how it will evolve. To address this problem, medical examinations (including audiograms) were carried out on a heterogeneous sample of 1,418 workers in Spain, from which demographic or personal data (gender, age, etc.), occupational data (noise level to which each individual is exposed, etc.) and other non-work-related factors (exposure to noise outside work, family history, etc.) were also gathered. Using Bayesian Networks, the conditional probability of an individual developing hearing loss was obtained taking into account all these factors and, specifically, noise level and length of service in the workplace. Sensitivity analyses were also carried out using the three scales (SAL, ELI and Percentage Hearing Loss Index), proving their suitability as tools the diagnosis and prediction of deafness. These networks were validated under the Receiver Operating Characteristic curve (ROC) criterion and in particular by the Area Under the Curve (AUC). Results: The results show that all three methods are deficient in so far as detecting preventive hearing problems related to noise in most workplaces. Conclusions: The most restrictive methods for detecting possible cases of deafness are the SAL index and the Percentage Loss Index. The ELI index is the least restrictive of the three methods, but it is not able to discriminate the causes of hearing problems in an individual caused by exposure to noise, either by its intensity level or by the time of exposure to noise. Practical Applications: The use of the three methods in the field of occupational risk prevention is extremely limited and it seems reasonable to think that there is a need for the construction of new scales to correct or improve the existing ones

Poultry production in Spain: New advances in feeding and nutrition practice.

Spain produces approximately 600 M broiler chickens per year and has a current laying hen census of 35 M birds. Production of other poultry species, such as turkeys and ducks, is quite limited. The number of birds slaughtered has remained quite flat for the last 10 years although final body weight (BW) has increased in this period by almost 200g per bird. The number of laying hens has decreased markedly (e.g. circa 50 M in 2010) and the proportion of brown -egg layers has increased from less than 10% in 1990 to more than 90% in 2013. In addition to egg color, brown eggs are preferred by the consumers because of bigger size and better shell quality

Influencia de la inclusión de diferentes fuentes y niveles de fibra bajo condiciones sanitarias diferentes sobre los rendimientos productivos en lechones recién destetados.

En general la inclusión de fibra en piensos de lechones se asocia con una reducción del consumo y de los rendimientos productivos (Wellock et al., 2008; Montagne et al., 2012). Sin embargo, diversos autores indican que la inclusión de cantidades moderadas de ciertas fuentes de fibra en el pienso podría mejorar los rendimientos productivos en lechones recién destetados (Mateos et al., 2006; Hermes et al., 2009). De hecho, Bach Knudsen et al. (2008) y Wellock et al. (2008) observaron que la inclusión de fibra en el pienso disminuyó la incidencia de diarreas (ID). Pluske et al. (1998) encontraron una relación positiva entre la ID y la inclusión de fibra soluble en el pienso. Sin embargo es frecuente incluir niveles de hasta el 4-5% de pulpa de remolacha en piensos comerciales para reducir el ID. La fibra soluble de la dieta podría actuar como un substrato fermentativo reduciendo el pH y alterando el perfil microbiano. Por otro lado, la fibra insoluble podría estimular el funcionamiento del tracto gastrointestinal y mejorar la sanidad de los lechones, reduciendo la actividad de bacterias perjudiciales. La respuesta a la inclusión de fibra en piensos para lechones puede estar condicionada por factores tales como el tipo y el nivel de fibra así como las condiciones higio-sanitarias de los lechones. En particular, la limpieza y desinfección de la nave son consideradas factores claves para limitar la incidencia de diarreas post-destete (Madec et al., 1998). El objetivo del presente trabajo fue evaluar el crecimiento y la incidencia de diarreas en lechones criados bajo condiciones higio-sanitarias adecuadas (naves limpias y desinfectadas) o inadecuadas (naves sucias) alimentados con dietas que diferían en el tipo y nivel de fibra utilizado

Influence of particle size of the main cereal of the diet on egg production of brown laying hens

The influence of the screen size used to grind the main cereal of the diet on egg production, gastrointestinal tract (GIT) development, and body measurements was studied in hens from 17 to 49 wk of age. Diets formed a 2 × 5 factorial with 2 main cereals (corn vs. barley) and 5 screen sizes of the cereal (4, 6, 8, 10, and 12 mm). Each treatment was replicated 5 times. No interactions between main cereal and screen size were observed for any of the traits studied. Cereal type and screen size did not affect feed intake, egg production, BW gain, or quality traits of the eggs. Eggs tended to be larger (P = 0.092) in hens fed the barley diet than in hens fed the corn diet. Also, feed conversion ratio tended to increase (P = 0.081) when the cereal of the diet was ground with a 4-mm screen as compared with the average of the other diets. At 49 wk of age, the relative weight (% BW) of the GIT and gizzard was greater (P < 0.05) in hens fed barley than in hens fed corn. An increase in the screen size increased linearly the relative weight of the GIT (P = 0.089), gizzard (P < 0.01), and liver (P = 0.056). None of the other GIT traits or body measurements was affected by the main cereal or the screen size. In summary, barley can substitute up to 45% of the corn in diets for laying hens without any adverse effect on egg production. Therefore, the use of one or other cereal will depend on their relative cost. An increase in screen size improved gizzard development but had little effect on hen productivity. Within the range studied, the size of the screen used for grinding the cereal had little effect on hen productivity, although the use of a 4-mm screen might increase feed conversion ratio and gizzard development

Role of fibre in broiler diets - Firend or foe?

The fibrous fraction of the feeds encompasses a group of heterogeneous compounds differing in chemical composition and physical properties (Graham and Aman, 1991, Bach Knudsen, 2001). Dietary fiber is the most used term to define the fiber fraction of ingredients and feeds, and includes cell walls, stored non-starch polysaccharides (NSP), and lignin (Bach Knudsen, 2001). Based on their physico-chemical properties, DF can be divided into soluble and insoluble fractions with distinct effects on digestive physiology and animal metabolism. Consequently, the benefits of fiber inclusion in poultry diets will vary depending on factors such as characteristics of the fiber source, type of bird, and digestive health status